Means for increasing the strength of electric currents.



L. DE FOREST. MEANS FOR INCREASING THE STRENGTH 0F ELECTRIC CURRENTS.

.APPLICATION min APR- 11. I9I2.

1,134,594 PatentedApr. 6, 1915.

' UNITED STATES PATENT; O FICE.

LEE 1m ronnsr, or rnnonm'o, CALIFORNIA, ASSIGNOR To name TELEPH NEsz TELEGRAPH coMraNY', A CORPORATION or D LAWARE.

- MEANS FOR INGRILlASING: THE STRENGTH OF ELECTRIC CURRENTS.

Specification of Letters Patent Patented Apr. 1915.

. Application filed April 11, 1912. Serial No. 690.113.

T0 allwhom'it may concern." v Beit known that'I,LnE .DE Eonns'r, a citizen of the United States, residing at Palo Alto, in the county of Santa Clara,

State of California, have made a certain.

new and useful Invention in cans for Increasingv the Strength of Electrical Currents, of which the following'is aspeclfication.

This, invention relates' to improvements in" means for transmitting sounds or human intelligence. by means oi electric currents either through conducting wires, or bythe radiation of electromagnetic waves, and particularly, to means employed for boosting or increasing the strength of the transmitted signaling current.

The object of the invention is to pro,- vide means for increasing the intensity of telegraphic or telephonic received signals transmitted with or without theuse of l ne conductors. I

Other objects of the invention will ap- .pear more fully hereinafter. The invention consists substantially in the construction, combination, location and arrangement, all as will be more fully hereinafter set forth, as shown in the accompanying drawings, and finally pointed out in the appended claim.

Referring to the accompanying drawings,

and to the various views and reference signs.

appearingthereon,-Figure 1. is a view,

somewhat diagrammatic, showing one form ceived signal currents.

of construction, embodying 'my invention wherein a homo-polar dynamo is employed to efi'ect the increased intensity bf the re- Fig. 2 is a similar view in top plan. v

The same reference sign occurs throughout'the several views to designatethe same art.- 7 p In accordancewith the 'principles'of my present invention, I propose to relatively move a closed conductor and-coils suitably connected up and through which the currentsto be amplified are conducted and which coils are associated'with a receiving apparatus. The relative movement of the closed conductor and 'the coils associated.

therewith, in the attainment of the objects and purposes of my invention, may be accomplished in any suitable or convenient.

manner, and in many different ways. Ordinarily I prov de a motor-dnve'n means for signals In accordance with my invention the intensity or amplitude ofthe received current impulses is increased without however varying essentia1ly,.or distorting, the waveform characteristic of the received impulses.

In Fig. 1, I have shown one arrangement embodying my invention wherein I employ magnets E which are placed with their 1 axis, or the axis of their cores, perpendicular to the plane of the conducting disk I The currents to. be intensified or amplified i are conducted through windings or coils placed upon the legs of the cores E}. Three of these magnet" E are shown, each of which carries two separate windings P 8?,-

co'nstituting, respectively, the primary and secondary coils of a; transformer, the. secondary winding of one set being connected to the primary coil of the next adjacent set or magnet, and so on. If desired, of course,

i all of the coils may be connected up in series, and with the telephone receiver T In either case there will takepla'ce three successive amplifications. I find that this amplifying process can be carried on almost indefinitely so that extremely weak or inaudible signal'pulsations or currents may be made very strong and the sound produced. or the work accomplished thereby,

increased. This is particularly so with suchsignals as are used in wireless telegraphy where it'i's of little consequence if the exact tone qualities of the received impulses are somewhat distorted, volume of sound being 'here the chief consideration. But with voice transmission the distortion observed with two or three successive ampliiications such asI have described is inconsiderable.

In the construction shownin Fig. 1 the "conductor I, may be rotated in any suitable or convenient manner, or-the relative rotation or movement 'ofsaid closed conductor and the cores of magnets E may be accomplished in many suitable or different ways. I have shown the conductor disk I as driven from a motor M for axial rotation of the former. y

In, Figl 2 I have shown diagrammatically an arrangement wherein two successive amplifications of the received current impulses are accomplished. In this arrangement a conductor or closed conductor I", is employed. The relative movement of the closed conductor and the magnet cores or coils is accomplished, by suitably rotating axially the conductor disk 1 In this arrangement two magnet cores E are employed which constitute cores for coils P S Two coils P S being associated with each core E The magnets are arranged with their pole ends presented toward and in close proximity to the side surfaces ofthe conductor 1 One of -the coils as P, receives initially the transmitted current impulses. tially currentimpulse receiving coil P is in series with the coil P .of the second amplifier. The final amplification of current impulses are received in the telephone T e Care should be taken in the design of such an amplifying homo polar generator as I have described, to reduce all but the useful eddy currents and all iron losses as far as possible, by proper lamination of the stator and rotor-bodies. For example, the stator S may be built up of soft iron punchings, the planes of which pass through the a is of rotation of the machine. Similarly, th rotor body can be of the form of a squirrel cage armature. Similarly, the laminated rings of the inner coil L, should not be com The coil S associated with the ini- In an apparatus for amplifying feeble electric currents or current impulses, a

transformer having its primary coil in circuit with the source ofcurrent to be amplified, its-secondary coil connected with the primary of a' second transformer, the secondary of thesecond transformer connected with a signal indicating device, and a conductor disposed with relation to both of said transformers to cut the magnetic lines of force thereof, and means for relatively moving'said conductor transversely netic lines of force.

Intestimony whereof I have hereunto set my handin the presence of the subscribing witnesses, on this 26th day of March A. D.,

LEE on FOREST. Witnesses:

A. COONEY, C. MELODY.

to the mag- 

